CMMVC8673E The volume is already mapped as a SCSI LUN which must first be unmapped/removed in order to create a subsidiary volume mapping.
Explanation
An attempt was made to create a subsidiary volume mapping, but the volume is already mapped as a SCSI LUN. Subsidiary LUN mappings are typically created or removed by the IBM® Spectrum Control Base Edition application. These mappings apply only to adminlun host types, and so it is unlikely that a storage administrator would encounter this message.
User response
Contact IBM Support.